Doug, the oil is perfectly normal. This oil is the reason that the flexible pipes should lead upwards to the regulator, so that the regulator is not contaminated by the oil. For a small charge, propane suppliers will "purge" your tanks to clear out any residues. You might like to do this every ten fills or so.
To obtain the fitting you describe, after failing at an Airstream dealer, I found a fitter at the local main propane distributor and got him to sort out the connections from his supply from the back of his truck. It involved several fittings in series to make the change in size. Good luck in your hunt.
Nick Crowhurst, Excella 25 1988, Dodge Ram 2500 Cummins Diesel. England in summer, USA in winter.
"The price of freedom is eternal maintenance."